Aerogels are porous solids with high surface areas that are made by forming a gel network and removing the solvent without causing pore collapse. Due to characteristics such as high surface area, high porosity and low density, these lightweight aerogels are attractive for use as thermal insulators, low dielectric substrates and catalyst supports.
In general, a typical silica aerogel used as insulation loses its high surface area pore structure above about 700° C. As the pore structure of the silica aerogel sinters, thermal conductivity increases, diminishing the insulating capabilities of the aerogel and limiting its upper use temperature. Additionally, commercially available fibrous insulation incorporating silica aerogel exhibits poor adhesion of the aerogel to the fiber reinforcement, resulting in loss of aerogel particles in handling and contributing to a loss of insulating capability.
Traditional seals for high temperature applications, such as thermoelectric power generation and aerospace applications, incorporate a woven ceramic fabric wrapped around a non-woven, blanket type ceramic insulation. These non-woven thermal blanket type insulations are highly non-uniform in fiber density and spacing, and do not provide as low a thermal conductivity as has been demonstrated for high temperature aerogel composites. Conventional blanket insulation is compressible and the thermal characteristics of the blanket are altered by the degree of compression.
There is a need for insulation that can be used at temperatures between 600-1000° C. Although existing blanket insulations may be used at these temperatures, it is desirable to replace existing blanket insulation with higher efficiency, lighter weight materials.